Using Charcoal as a Decorative Mulch Topping: Pros and Cons

Homeowner wants to spread coal over mulch in a bed with holly, forsythia, French lilac (fabric + mulch already).

Charcoal Is Safe But Low-Nutrient

• Not toxic to plants.
• Dilutes soil nutrients if too thick.
• Retains moisture → fungus risk if >3 in total mulch depth.

Application Tips

• Thin layer (½–1 in) over existing mulch.
• Taper to zero at plant bases (prevents bark rot).
• Fabric underneath minimizes soil mixing.

Verdict

Looks striking, suppresses weeds, safe if not overdone.